Dithiocarbonate diesters are organic compounds which exhibit a broad range of valuable properties. Various species have found application as rust inhibitors in oil formulations, rubber plasticizers, cytostatic anti-tumor agents, antituberculosis agents, ovicides, insecticides, herbicides, fungicides, plant growth regulators, photographic silver halide emulsion stabilizers, and the like.
U.S. Pat. No. 2,476,166 describes .alpha.,.alpha.'-dithiocarbonodialiphatic acids which are useful as rust inhibitors in turbine oils.
U.S. Pat. No. 2,775,568 describes the plasticizing of rubbers with dithiocarbonate esters such as dipentachlorophenyl dithiocarbonate.
U.S. Pat. No. 3,151,024 describes new biological toxicants with a dithiocarbonate diester structure: ##STR3##
U.S. Pat. No. 3,510,486 describes the preparation of ovicidal agents such as 6-methylquinoxaline-2,3-dithiol cyclic carbonate: ##STR4##
The most common synthesis method for the production of dithiocarbonate diesters involves the reaction of phosgene and an appropriately selected mercaptan: ##STR5## In order to prepare an unsymmetric dithiocarbonate diester, an intermediate chlorothioformate is isolated and purified, and then reacted with a second mercaptan: ##STR6##
The use of a hazardous starting material such as phosgene is a serious disadvantage of the above described standard method of preparing dithiocarbonate diesters. Further, the synthesis of unsymmetrical dithiocarbonate diesters is not accomplished in a convenient and efficient manner.
Accordingly, it is an object of this invention to provide a process for preparing symmetrical and unsymmetrical dithiocarbonate diesters, without the use of a phosgene type of hazardous starting material.
It is another object of this invention to provide a process for dithiocarbonate diester production which proceeds via a novel isoxanthate salt reactant.
It is a further object of this invention to provide a novel class of isoxanthate salt compounds, and to provide a process for their production.
Other objects and advantages of the present invention shall become apparent from the accompanying description and examples.